Configuration Guide User guide

FastIron Configuration Guide 1631
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Chapter
38
MLD Snooping on FastIron WS and
Brocade FCX and ICX Switches
Table 274 lists the individual Brocade FastIron switches and the Multicast Listening Discovery
(MLD) snooping features they support. These features are supported in the Layer 2, base Layer 3,
edge Layer 3, and full Layer 3 software images.
MLD snooping overview
The default method a device uses to process an IPv6 multicast packet is to broadcast it to all ports
except the incoming port of a VLAN. Packets are flooded by hardware without going to CPU, which
may result in some clients receiving unwanted traffic.
Multicast Learning Discovery (MLD) Snooping provides multicast containment by forwarding traffic
only to those clients that have MLD receivers for a specific multicast group (destination address).
The device maintains the MLD group membership information by processing MLD reports and
generating messages so traffic can be forwarded to ports receiving MLD reports. This is analogous
to IGMP Snooping on the Brocade Layer3 switches.
An IPv6 multicast address is a destination address in the range of FF00::/8. A limited number of
multicast addresses are reserved. Since packets destined for the reserved addresses may require
VLAN flooding, these devices do not snoop in the FF0X::000X range (where X is from 0 to F). Data
packets destined to these addresses are flooded to the entire VLAN by hardware, and mirrored to
CPU. Multicast data packets destined to addresses outside the FF0X::000X range are snooped. A
client must send MLD reports in order to receive traffic. If an application outside the FF0X::000X
range requires VLAN flooding, you must configure a static group for the entire VLAN.
An MLD device periodically broadcasts general queries, and sends group queries upon receiving a
leave message to ensure no other clients at the same port still want this specific traffic before
removing it. MLDv1 allows clients to specify which group (destination IPv6 address) on which to
receive traffic. (MLDv1 cannot choose the source of the traffic.) MLDv2 deals with source-specific
multicasts, adding the capability for clients to INCLUDE or EXCLUDE specific traffic sources. An
MLDv2 device's port state can either be in INCLUDE or EXCLUDE mode. There are different types of
group records for client reports.
TABLE 274 Supported MLD snooping features
Feature FESX
FSX 800
FSX 1600
FWS FCX ICX 6610 ICX 6430
ICX 6450
MLD V1/V2 snooping (global and
local)
This chapter describes MLD
snooping on the FWS and
FCX. For information about
MLD snooping on other
FastIron devices, see
Chapter 37, “MLD
Snooping on FastIron X
Series Switches”.
Yes Yes Yes Yes
MLD fast leave for V1 Yes Yes Yes Yes
MLD tracking and fast leave for V2 Yes Yes Yes Yes
Static MLD and IGMP groups with
support for proxy
Yes Yes Yes Yes